[WARNING - Post-mortem pics] Betta death and disease needs ID'ing


Hello everyone.

Not having much luck with my main tank. I lost all 13 of my guppies due to a mysterious disease causing stringy white poop a month ago. This disease only affected guppies and had a 100% fatality rate, despite over a dozen medications being tried and aggressive isolation being performed. After the last one died, I ran UV in the tank for several weeks before introducing more guppies. So far, none of the new ones are sick.

Unfortunately my bettas are showing signs of health problems that I am worried are a recurrence of that disease. We came back from a few day's holiday to find one of our beautiful 6 month old girls was behaving a bit reclusively. No other symptoms or injuries that I could see, just something about her behaviour I couldn't quite put my finger on. A few days later we found her dead in one of her favourite napping spots. There's a post-mortem pic below if it helps:


At the time I just thought it was a one off due to lack of outward symptoms. But our other betta has now started pooping weirdly for the past week, and you guessed it... stringy white/brown.


I'm really worried the stringy white poop disease is back. When the guppies had it, we tried every anti-parasitic medication you can get in the UK (prazi, flubendazole, levamisole) both individually and in combination. We tried every anti-bacteria we could find, anti-fungus, anti-protozoan, and broad-spectrum meds. Absolutely no effect, it killed everything it touched.

But I know white stringy poop is not necessarily a sign of infection, and none of the 5 new guppies are symptomatic. Can anyone explain the symptoms our new betta is having?

I'll fill out the FAQ template in a separate post to avoid clutter. Thanks all


Could be an internal parasite and that is why dosing the water column to treat hasn't been effective for you. Can you get seachem products in the UK?


What is the water volume of the tank?: 180L
How long has the tank been running?: 11 months
Does it have a filter?: Yes
Does it have a heater?: Yes
What is the water temperature?: 28*C
What is the entire stocking of this tank? Formerly 2 female betta now down to one, 7 kuhli loach, 10 otocinclus, 3 neon tetra, 5 guppies

How often do you change the water? Weekly
How much of the water do you change? 20%
What do you use to treat your water? Fluval dechlorinator
Do you vacuum the substrate or just the water? Just water

*Parameters - Very Important
Did you cycle your tank before adding fish? Yes
What do you use to test the water? API droplet test kit
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.
Ammonia: 0
Nitrite: 0
Nitrate: 10
pH: 7.5

How often do you feed your fish? Daily
How much do you feed your fish? Pinch
What brand of food do you feed your fish? Varied, King British, Fluval, Tetra
Do you feed frozen or freeze-dried foods? No

Illness & Symptoms
How long have you had this fish? Sick betta is about 6 months old
How long ago did you first notice these symptoms? One week ago
In a few words, can you explain the symptoms? White stringy poop
Have you started any treatment for the illness? None yet but tried over a dozen medications when the guppies were sick, see OP
Was your fish physically ill or injured upon purchase? No
How has its behavior and appearance changed, if at all? No

Explain your emergency situation in detail. See OP
Could be an internal parasite and that is why dosing the water column to treat hasn't been effective for you. Can you get seachem products in the UK?

Surely one of the anti-parasite medications would have dealt with it, though? We also performed a microscopy on the stringy poop and couldn't see any parasites either sadly. We can get Seachem products, but not all of them (we can't get anything that has antibiotics eg metranidazole).


You could try metroplex mixed with seachem focus in food. But first will you post more pics of the sick betta? Include side and top view shots if you can


Just thought I'd update this. The white stringy poop was a false alarm, the disease hasn't come back and the betta started pooping normally after a few days. Cheers all.

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